The chemical composition of almond hulls has been the source of previous comment in the literature. For example, in U.S. Pat. No. 4,482,761 to Chao, the production of inositol and other sugar alcohols, and of sugars. The water extract of almond hulls is disclosed. In this patent, the use of molecular sieves to separate these useful compounds is also disclosed. Sequeira et al, "The carbohydrate composition of Almond Hulls", J. Agri. Food Chem. Vol 18 (1970) pp 950-951 is another discussion of the composition of almond hulls.
Almond hulls are a natural product forming a part of the almond fruit itself. They are produced as a by-product of the processes of producing the most-utilized part of the almond fruit, namely the stone.
It is not a matter of common knowledge, nor well understood in industry and commerce, that the source of the almond nut is a fruit tree. The sweet almond (Prunus amygdalus, or Amygdalus communis) is specifically a stone fruit (drupe), in which the fleshy part, the mesocarp or "hull", is derived from the ovary of the flower and surrounds the shell (endocarp), teguement (thin papery covering), and finally the stone or "nut" itself. Almond trees are currently cultivated commercially solely for the value of the edible nut, or in the case of the bitter almond, for the flavoring extracts expressed from the otherwise inedible nut. Almonds are most closely related to other stone fruit, such as peach (Prunus persica), apricot (P. armeniaca) and plum (P. domestica, P. instititia, et al.) in which the stone is indeed a stone in the common understanding and is not edible, whereas the mesocarp (not referred to as a "hull") is, and it and forms the basis for the commercial exploitation of these fruit.
The process of growth, maturation, abscission, and senescense of the almond fruit, is such that early in its growth stage the "hull" can be eaten by humans then it prossesses pleasing taste, texture, and nutritional value, whereas by maturation and thereafter the hull is leathery in texture and astringent to the taste, although its nutritional value has actually increased. Unfortunately this increase in nutritional values is accompanied by the presence of other chemical components which can temporarily sicken a human.
As recently as thirty years ago, the nutritional value of the almond hull was not sufficiently understood, and after harvest of the nuts, in California the hulls were either used for landfill, burned for removal, or perhaps burned for their fuel value. Starting about thirty years ago, agricultural scientists in California introduced and pioneered the use of almond hulls in animal feed, primarily cattle, in which animals the chemical components troublesome to humans do not upset the animals, and nutritional value is obtained at low cost.
The inventor in this instant patent application has observed that several chemical components of almond hulls, present after fruit maturation, have individual and important commercial values, and has devised a commercial process to separate and purify each of them, leaving very little to waste. For example, prior to the introduction of the use of hulls for animal feed, almond hulls had a negative or zero commercial value. Currently, for feed usage, almond hulls have a value averaging about $50/ton. The process invention described herein can raise the value of the almond hull (as separate components) to approximately $800/ton.
The success of this process depends upon understanding the physiology and biochemistry of the mature almond fruit and the precise application of commercial separation science techniques to selectively extract components of value without destruction or waste of any of the components.
It is an object of this invention to produce the following as products: vegetable tannins, dietary fiber, and syrups or sweeteners, and potential coproducts such as sorbital, fructose, and inositol.